The present invention relates to a vehicle-body front structure of a vehicle, in which a crash can is provided between a bumper beam and a front side frame.
Conventionally, a technology is known, in which a pair of right-and-left front side frames extending in a vehicle longitudinal direction is provided at a vehicle-body front portion so that an impact load is absorbed by the front side frames crushing in a front-end collision of a vehicle.
Herein, the front-end collision of the vehicle occurs at a vehicle-body portion which is located on an outward side, in a vehicle width direction, from the front side frame in some cases. This kind of front-end collision in which the vehicle body collides with an object with a small overlap-width in the vehicle width direction (e.g., about 25% of the vehicle width) is sometimes called “a small overlap collision.”
In a case in which the object of the small overlap collision is a pole member, such as a utility pole or traffic sign, this pole member sometimes collides in a manner of sinking into a portion between the front side frame and a front wheel. In this case, there occurs a problem in that a transmission efficiency of a load transmitted to the front side frame may deteriorate. Further, even in a case in which the object of the small overlap collision is a non-pole member, such as another vehicle traveling in the opposite direction, the transmission efficiency of the load transmitted to the front side frame may improperly deteriorate, compared with a case in which the object and the vehicle body collide with each other in a wide overlap-width in the vehicle width direction. Therefore, there is a problem in that, in the case of the small overlap collision, the amount of impact absorption by deformation of the front side frame becomes so small that the impact load may be transmitted to a vehicle-compartment side improperly easily.
US Patent Application Publication No. 2004/0195862 A1 discloses a vehicle-body front structure shown in FIG. 10, which may become one countermeasure against the above-described problem. In a conventional structure shown in FIG. 10, a fork member 150 which extends forward, forking into two branches, is disposed between a front end of a front side frame 104 and a bumper beam 110. This fork member 150 comprises a straight-extending member 152 which extends forward from the front end of the front side frame 104 without slanting and an outward-slant member 154 which extends forward from the front end of the front side frame 104, slanting outward in a vehicle width direction. A rear end portion of the straight-extending member 152 and a rear end portion of the outward-slant member 154 are connected by bolts. According to this structure, even in the case of the small overlap collision, an impact load received at the outward-slant member 154 is transmitted to the front side frame 104, so that the impact can be absorbed by effectively deforming the front side frame 104. Thereby, the impact transmitted to a vehicle-compartment side can be reduced.
In general, a crash can is disposed between the front end of the front side frame and the bumper beam. In this case, in a case of a low-speed collision of 15 km/h, for example, the collision load can be absorbed only by deformation of the crash can, without any breakage of the front side frame. Thereby, repair costs can be reduced.
In this regard, in the above-described conventional structure shown in FIG. 10, if the above-described straight-extending member 152 has a low rigidity like the crash can, it may be considered that the collision load can be absorbed by deformation of the straight-extending member 152, without any breakage of the front side frame 104, in the low-speed collision. In this case, the straight-extending member 152 can be considered as the above-described crash can.
However, since not only the straight-extending member 152 but also the above-described outward-slant member 154 are arranged in front of the front side frame 104 in the structure shown in FIG. 10, when the impact load in the low-speed collision is absorbed by the deformation of the straight-extending member 152, the outward-slant member 154 gets broken as well as the straight-extending member 152. Therefore, the repair costs may increase more.
Meanwhile, in the conventional structure shown in FIG. 10, if the rigidity of the straight-extending member 152 is so large that the straight-extending member 152 cannot function as a crash can, the impact is directly inputted to the front side frame 104 even in the low-speed collision, so that the front side frame 104 gets damaged easily. Consequently, the repair costs may increase further.
Further, in general, while the bumper beam is provided such that its both ends extend to connection portions to crash cans, when the structure equipped with the outward-slant member 154 shown in FIG. 10 is applied, it is necessary to extend both ends of the bumper beam 110 further up to connection portions to the outward-slant member 154. Accordingly, it may be necessary that both end portions of a bumper 120 are bent rearward in a squire manner so as not to interfere with the both end portions of the long bumper beam 110. Therefore, the both end portions of the bumper 120 cannot be curved rearward smoothly in a shape illustrated by a two-dotted broken line R of FIG. 10, for example. Consequently, there is another problem in that the design of the vehicle-body front portion may be restricted.